Photographic coating



' better Photographic rmuits without Prensa July 4, 1944 UNITED STATE 5PATENT 2.352322 PHOTOGRAPH) COATING.

. John Dessauer, lrondequoit, N. Y.,

I The Haloid Company, Roe

poration of New York 'No Drawing.

2 Claims. (Cl. 95-1) This inventionrelates to a photographic lightsensitive coating and has for its object to aflord an, improved coatingparticularly adapted for photographic enlarging Paper, contact printingpaper. and reflex copy P p r.

One purpose of: the "invention is to afford a properly'completing agiven exposure on enlarging paper and which a high degree of sensitivitywhen exposed. to light within the gen-* coating requiring less time thanheretofore for x OFFICE a'ssignor to heater, N. Y a cor- ApplicationFebruary 2, 1942, Serial No. 429,280 I coating after storage andmaintaining its efll-, clency regardless of its age.

-It is a further purpose of the. invention to provide a coatingsensitized with'a dye that gives the best range for color sensitivitypreferably between 4400 and 5200 angstromathus affording. a moreselective color control, and which also greatly reduces the exposuretime required witheralregion of the spectrum comprehended between 4400and: 5200 angstroms, 'the spectral wave light region within which thelight most' generally used for photographic exposures has a highlysatisfactory actinic value.

Another purpose of the invention is to ailord acoating with extremesensitivity in the'spectral region within which the more eilicientresults are had for most color separation work.

A further object of the invention is to aiford a coating containing adye that is not sensitive to the pH value of an emulsion and does notlose sensitivity in the presence of halogen andfree silver ions but isstable and influenced very little by such factors so that instead ofimpairing the stability or keeping qualities of the emulsion as isthecase with dyes heretofore used, it has the further advantage ofimproving the character and lasting qualities of theemulsion. I Anadditional object of the invention is to ime prove the resultsobtained-with as well as the quality of reflexcopy paper which isexposed ina contact printer with the coated side out and the subject tobe'copied is placed face down against the coating, with a light sourcearranged todirect light through'the coated light sensitive Piper on tothe subject to be copied, the light being absorbed by the printedportions and reiiected back on to the light sensitive coating where itstrikes anunprintedor white portion.

In the production of reflex copy .paper,- the -best results haveheretofore been obtained by us ing a sensitizing ye in the emulsionandlin 117' in this desirable region of the spect I Another object ofthe invention'is to afiord a coating for photographic papers containinga An additional object of the invention is af ford a chloride emulsioncoating-having an exposure speed as fast as that of a bromid emulslonwhile retaining the desirable advantages of the chloride emulsion.

The purposes of the invention may be accomplished with a silver chlorideemulsion, or a sil-. ver' bromo-chloride emulsion containing approximately one-third to one-half bromide and twothirds to one-halfchloride, by dding the dye 7 solution to the emulsion either during themixing process at' any time after the silver halide: is formed, orshortly before the emulsion is coated on the paper or support. The dyesolution may consist of' one part of dye to one thousand or two thousandpartsof solvent, either water tion a desensitiser, the function or whichis to desensltize the emulsion so, asto slow down its fi m-speed andmakpoesibletheuseofsuch a paper or alcohol, and satisfactory results I havebeen obtained by adding: 0.1 to 02 gram of such a dye solution toapproximately forty pounds of Dyes which have been found iscllEiCNfikNOi, acridine orang 01' tetra-i in subdued daylightbut adesensitizer has a practical disadvantage since its desensitiring actionon the flexcopy P per thatwill attain etmallys d'and v the of a thuspreventing deterioration the coating and renders it unfit fol-successfuluse after it has been stored for a length of time, and itis anadditional; purpose of the invention to afford a remethyl diaminoacrldin chlorhsdrat. theformula for which is CnHhNsCH-ZDOB, andacrlilavin or diamino methyl acridinnimchlorid-chlorhydrat,formulaforwhichis Q14E1M-i-HCI. These .are acridine dyes,,eachcontaining two benzene rings united by carbon and nitrogen respectively,W

' and experiments already conducted indicate that the invention can be,successfully carried out with any otthe satisfactory in 1 W; the resultsas stated above are phos-f phi'ne or chr'ysanilin nitrate, theformula'jfor These dyes give a highly satisfactory degree of sensitivityin the region of the spectrum between 4400 and 5200 angstroms with anextremely fast exposure speed in relation to the initial speed sult andis easier to prepare and handle than a bromide emulsion coating.

.The dyes herein disclosed enable the manufacture of coatings that areparticularly adapted to color photography work by giving a fast exposurespeed within the general spectral region from 4400 to 5200 angstroms.Spectrograms made from coatings sensitized with acriflavin, phosphine,and acridine' orange show high speed sensitivity at 4400 to 4800angstroms, 4600 to 5200 angstroms, and 4400 to 5200 angstromsrespectively, all within the spectral region that is best adapted tocolor separation work.

Most printing'and exposing of photographic paper is done with Mazdalight which has increased actinic radiation toward the longer wavelengths and the dyes herein disclosed sensitize the emulsion to colorwithin a spectral region that is well adapted and extremely efllcientwhen working with Mazda light.

The most satisfactory results have been obtained with silver chlorideemulsion, although it is possible to use the dyes with some degree ofsuccess with silver chloro-bromide emulsions containing not more thanone-half bromide.

The dyes disclosed, owing to their exposure speed, permit the use of aslow emulsion and hence one of low silver content, thus reducing costparticularly in the case of contact papers. The dyes disclosed arestable as against the pH value of an emulsion or the halogen and freesilver ions which it contains and have no deteriorating influence on thecoating, the emv ciency of which is not reduced or impaired with age,but on the contrary, the quality of the coating appears to be improvedby the dye, so that no fogging is present and the photographic resultsare excellent.

When used for reflex copy paper, the use of a desensitizer isunnecessary and the keeping quality of the paper is considerably betterthan when a desensitizer is employed while the speed in relation to thenatural emulsion is quite sumcient for practical and successful results.

The dyes disclosed are of low cost, simple to produce, easily obtainablecommercially, and they can be incorporated readily in the emulsion owingto their chemical nature. They impart to the coating of enlarging papera fasterspeed relatively to the natural emulsion than dyes heretoforeused for this purpose, and help to give the necessary keeping quality tothe emulsion that is required for practical requirements. The resultsobtained are substantially better both as to the image obtained and thestability of the coating than enlarging papers heretofore obtainable,and when used for contact papers, an emulsion with a lower silvercontent than heretofore can be employed without aifecting the resultingimage. Thus the ease of handling and other advantages that characterizea chloride emulsion are had while retaining the speed of a bromideemulsion but without any of the undesirable characteristics of thelatter.

Other advantages and results will develop from use of the dyes set forthin a light sensitive silver haloid coating, and this application isintended to cover such adaptations of the invention as may come withinthe purposes of the improvement and the scope of the following claims.

I claim:

1. A photographic coating which can be exposed for printing in subdueddaylight under Mazda light and contains one of the group of emulsionsconsisting of silver chloride emulsion, and silver bromo-chlorldeemulsion containing approximately one-third to one-half bromide andtwo-thirds to one-half chloride, and an acridine dye which enhances thekeeping power of the emulsion and imparts to the coating high speedsensitivity confined within the spectral region between not less than4400 angstroms and not more than 5200 angstroms.

2. A photographic coating which can be exposed for printing in subdueddaylight under Mazda light and contains one of the group of emulsionsconsisting of silver chloride emulsion,

and silver bromo-chloride emulsion containing approximately one-third toone-half bromide and two-thirds to one-half chloride, and oneof thegroup of dyes consisting of chrysanilin nitrate, tetramethyl diaminoacridin chlorhydrat, and diamino methyl acridiniumchlorid-chlorhydrat,which enhances the keeping power of the emulsion and imparts to thecoating high speed sensitivity confined within the spectral regionbetween not less than 4400 angstroms and not more than '5200 angstroms.

J OHN DESSAUER.

